Attached is my design for an RF Amplifier for an AM Radio using an LT1222 OP AMP.

This RF design is calculated to give a 40dB gain (100V/V) output @ 1.4MHz, however with this configuration and providing 1.4MHz via function generator the output waveform is attached and does not give the desired output.

Yes make Ra 5k & Rb 51 ohms and add 10pf to pin 5 to ground. Add some good high frequency decoupling to the power supply while your at it. It would help to know the application, but this might stop the oscillations at least.

Also in response to application, the RF amp will be fed an antenna instead of function generator signal. And the output of the RF is going to a bandpass filter. Also if you dont mind me asking, what does the capacitor to pin 5 help with?

Also in response to application, the RF amp will be fed an antenna instead of function generator signal. And the output of the RF is going to a bandpass filter. Also if you dont mind me asking, what does the capacitor to pin 5 help with?